The present invention relates to a lens focus control apparatus, and more particularly to apparatus for displaying the desired direction of movement of a focus lens and for adjusting the current position of the focus lens to bring into exact focus a video camera or a camera recorder (camcorder). The present invention uses an inner focus lens method in which the focus length is manually adjusted.
In general, there are two basic focus lens drive methods. In a front focus lens method, a focus lens is positioned in front of a camera for easy manipulation of the focus lens by hand. In an inner focus lens method, the focus lens is positioned in the middle of the camera and the focus length of the focus lens is adjusted by driving a focus lens drive motor.
The inner focus lens method is limited by the drive characteristic of the focus lens. Accordingly, when the camera is greatly out of focus, the user cannot judge the correct direction of movement of the focus lens to bring the camera into exact focus until considerable time, e.g., about one or two seconds, has passed. Also, since the user manipulates the focus lens to move it to the in-focus position, he or she cannot easily judge whether or not the direction of movement is correct. One prior art method and apparatus for discriminating and displaying a focus state during the manual focus adjustment is disclosed in U.S. Pat. No. 4,572,643.